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Unread 01-20-2012, 07:21 PM   #1
I6CJ7
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The correct way to power an HEI

The red 10-gauge power wire that comes out of the fire wall that used to power the old computer for the carb...this is powering all of the dash lights and gauges, so why are we using this to power our HEI when its has to power all those components as well as our new HEI distributor that requires a fair amount of juice?

I would think this would stress that undersized wire even more. Not to mention not supplying proper voltage for the HEI.
Instead shouldn't we just run a wire from the battery to a switched ignition relay, then straight to the dizzy? I read somewhere a "DUI" dizzy needs 14.5 volts to operate at its full potential.

Could the standard jeep relay for the starter be used for this? Or should it have its own dedicated relay?

Anyone have any pictures or diagrams of this?

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Unread 01-20-2012, 07:38 PM   #2
JeepHammer
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Ok! Lets start with some basics...

The MORE voltage you pump into your ignition coil,
And the cleaner you switch that power 'ON' and 'OFF' to that coil,
The more spark energy OUTPUT you will get from that coil.


Notice I said VOLTAGE...
Voltage is a function of AMPERAGE, or VOLUME of energy.


Think if it like water pressure in a pipe.
VOLTAGE IS PRESSURE,
AMPERAGE IS VOLUME.

If you can't move enough VOLUME, you won't build 'PRESSURE'...

Not enough AMPERAGE, you won't build VOLTAGE.

This can be GRAPHICALLY DEMONSTRATED by using a volt meter on the battery when you start your vehicle.
You will show around 12.6 volts at the battery, but when the starter draw large AMPERAGE,
The voltage at the battery terminals will DROP to around 7-10 volts.
If it's hard start where you crank on the starter a while, you can watch that terminal voltage drop down to around 3-5 volts.

When you let up on the key, the voltage will IMMEDIATELY RECOVER up to about 9 or 10 volts since there isn't any load on the battery.
After the battery has had time to recover, converting CHEMICAL ENERGY INTO ELECTRICAL ENERGY,
The voltage will come up even more...

You are draining away the AMPERAGE at too high of a volume, and the VOLTAGE DROPS since there isn't any 'VOLUME' to feed the starter fast enough...

-----------------------------------------------------------------------

So taking that into account,
When VOLTAGE drops, it means you are sucking too many AMPS on the feed wire to any given electrical load, including the ignition coil.

------------------------------------------------------------------------

SO,
When your Jeep has ONE EACH, 10 Ga. wire from the starter relay ('Solenoid') to the fuse block,
And that ONE 10 Ga. wire is expected to power up the head lights, tail lights, brake lights, park lights, heater motor, dash lights, all the gauges...

AND THE IGNITION, WHICH HAS A 10 Ga. Wire connected to it for a REASON...
It's not likely that single 10 Ga. wire going into the fuse block is going to do any of those jobs particularly well.

A 10 Ga. wire is rated for 32.5 AMP when in continuous use.
I'd call every powered up accessory in the vehicle a CONTINUOUS LOAD.
LINK TO BROWN & SHARP SCALE SHOWING THE CAPACITY OF COPPER CONDUCTORS,
LINK: http://www.civilianjeep.info/Wiring/B&Sscale01.gif

SO,
You are using ONE 10 Ga. wire to the fuse block,
Then you are sucking amps in all directions,
Then you expect a 10 Ga. wire from that same fuse block to supply a FAST amperage charge to the ignition coil when it saturates...

AIN'T GONNA HAPPEN!

--------------------------------------------------

The 'Conventional' way to connect an HEI to a Jeep wiring harness is to plug the old coil Positive wire into the HEI and run it that way.

With the Resistor Wire still in that particular circuit, you are getting some were around 3 volts to the coil when it tries to saturate...

You are only getting 6 to 8 volts at virtually NO LOAD through that resistor, fuse block, fusible ink and 10 Ga primary wire, the ignition fuse, the old, burned ignition switch, about 20 or so old, corroded electrical connectors, and under size wiring under the dash,
And that's AFTER the head lights, tail lights, brake lights, heater, radio, tach, ect. have all consumed amperage...
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Unread 01-20-2012, 07:58 PM   #3
JeepHammer
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So, lets get back DIRECTLY to the HEI ignition in specific.

IF YOU DO NOT SUPPLY THAT HEI WITH A CLEAN VOLTAGE FEED,
LARGE ENOUGH TO SUPPLY UP TO 12 AMPS INTERMITTENTLY,
YOU ARE NOT GETTING FULL VALUE OUT OF THAT IGNITION COIL.

HEI's average between 6 to 6.5 amps AVERAGED,
That's 12 to 13 amps when the coil is trying to saturate, then virtually nothing to operate the module when the coil is 'Discharging' or in 'Dwell' mode.

According to Brown & Sharp, the industry standard in electronics,
that should take a 14 Ga. wire MINIMUM.

Consider the coil is a DEAD SHORT when it's saturating, and that current has to be delivered in a VERY short period of time,
A 10 Ga. wire isn't out of the question.

GM knew this,
GM used a 12 Ga. wire with a HEAT RESISTANT INSULATION,
Since the 12 Ga. wire they used would HEAT UP during operation.

A 'Common' 10 Ga. wire with Vinyl insulation will NOT heat up during operation to the point you need a special heat resistant insulation,
AND it will deliver the current to the ignition coil without problems.

You also need to have a CLEAN voltage source,
Something that doesn't have heater motors cycling the current adding switching 'Noise' to the line,
Turns signals clicking on and off, Head lights draining amperage, ect.

So the 'Correct' way to do the ignition is the same way GM does it on the fuel injected vehicles for years. Use a power relay to the ignition...

--------------------------------------------------------

Use the old Ignition wire to switch 'ON', or ACTIVATE the power relay.
It's easy to wire, simply two wires to the relay, one from the old ignition 'Coil' wire to the $85 terminal on a common relay,
And a 'Ground' or battery NEGATIVE wire to the #86 terminal on a common relay.

Other two terminals on the relay are for a CLEAN SOURCE from battery or better yet, the starter relay ('Solenoid'), battery cable side, to the #30 terminal on the ignition relay,
And a connection from the #87 terminal on the relay to the HEI distributor.

10 Ga. wires from starter relay to ignition relay, and from #87 to HEI for large gauge clean supply to the distributor.

The same realy used in the harness of EVERY Jeep with a manifold heater.
If it will supply a clean, solid current load to that heater, it will supply the HEI distributors!
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Unread 01-20-2012, 08:16 PM   #4
JeepHammer
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Ignition coils are simply 'transformers'....

The more voltage you put into the PRIMARY windings,
The more SPARK ENERGY you are going to get out of the SECONDARY WINDINGS.

With a common vehicle ignition, you are limited to 14.5 volts or less.
14.5 volts is all the battery will tolerate without overheating and failing quickly,
So with common vehicle voltage, it's a 14.5 volt top end limit.

A 12 to 14 volts, the ignition coil BARELY has enough time to SATURATE MAGNETICALLY, so it can produce an induction discharge when the power to the primary side is cut off.

So for the real world applications,
You BARELY have enough output spark energy from an ignition coil to keep that engine running.

It DOES NOT make sense to restrict that current going to the coil by using overloaded circuits,
Small gauge wiring, switching signal 'Dirty' current, resistors in the wiring, or 20 old, corroded contacts.

Now, remember, I said VOLTAGE to the coil builds the magnetic field so the coil can saturate...

A CDI (Capacitive Discharge Ignition) throws about 400 to 600 volts at the coil, depending on what type of CDI module you have.
With this increased, and very CLEAN voltage going to the coil, you can saturate the coil fast enough to fire the plug around 6 times!

At 12 to 14 volts, you BARELY can get ONE firing of the plug, and as RPM goes up and the time the coil has to saturate goes down correspondingly,
The coil output (spark energy) gets weaker and weaker...
Since as RPM increases, saturation times DECREASE...
INCREASED CURRENT TO THE IGNITION WILL HELP WITH THIS SITUATION.

CDI's solve the problem by throwing 400 to 600 volts at the coil, dramatically DECREASING the saturation times...

If you don't want to go with a CDI,
Then use a large gauge wire, A CLEAN voltage source, and keep the wiring runs short between voltage source (Starter Relay/battery cable connection) and the ignition.

-------------------------------

THE NEXT PART IS SWITCHING...

It takes a MOVING magnetic field to INDUCE a secondary discharge (Spark Energy)
The faster that magnetic field moves, the more current it's going to INDUCE in the secondary windings...

A SLOW SWITCH turning the current 'On' and 'Off' to the coil (The module's job) will ruin the SPEED of that magnetic field collapse through the secondary windings, and you will loose spark energy...

There isn't much you can do about the switching transistors in the HEI module.

But there IS something you can do about the current that module gets to switch 'ON' and 'OFF'.
The more current available when that transistor CLOSES the circuit and starts saturating the magnetic field,
The faster that magnetic field is going to reach full strength.

If there is 'Noise' on the line from the blower motor, other electrical accessories, like blinkers, radio, ect.
The magnetic field is going to fluctuate and NOT reach full saturation as quickly.
More 'Ramp' time to reach full magnetic saturation means LESS output on the secondary side.

The coil MUST 'Ground' through the module,
So if that module has a DEDICATED GROUND WIRE FROM THE MODULE TO THE BATTERY NEGATIVE,
The coil will saturate faster since the circuit is easier to complete.

When I tell people to use a 'Long Screw' through the 'Ground' terminal in the module, then add a wire and a nut to the bottom side,
Ground that module DIRECTLY instead of torturing the circuit trying to ground through the aluminum housing, the engine block, the head, then finally to a rusty bolt at the battery cable,
They look at me like I have a third eye in the middle of my forehead.

It's simple electrical FACT you MUST cleanly complete a DC CIRCUIT back to the NEGATIVE of the power source to have an efficient circuit.
So just having a large gauge feed wire isn't always enough, you MUST complete the circuit with a 'Ground' wire to a solid battery NEGATIVE source to make that coil primary circuit work well.

The next little upgrade you can do is use a HIGH QUALITY module with large current capacity transistors,
And transistors that switch 'ON' and 'OFF' cleanly!

You should see what passes for module transistors in some of these 'China' and 'Discount' modules these days!
We call it 'Ramp Time'.
When you watch that power come through that transistor on an oscilloscope, you are looking for VERTICAL LINES off the base line, or 'Zero' voltage line.

You want to see that voltage jump from ZERO to 'Battery Voltage' right straight up, or as close to a vertical line as possible...

When you see it lean over at an angle, where it looks like a 'Ramp' instead of switching clean...
That's were we get 'Ramp Time' from.

The cleaner the power switches 'ON', the more time the coil will have to saturate.
The cleaner the power switches 'OFF' the faster the magnetic field will collapse, and induce a larger secondary (Spark Energy) charge to the spark plugs.

When it takes a long time to 'Ramp Up', you loose saturation time.
When it takes a long time to 'Ramp Down', you don't get that magnetic field collapsing at a speed that will induce secondary discharge...

Using a good module with clean, vertical ramp angles will give you MUCH more spark energy out of the ignition coil...

--------------------------------------------------

Spark Plug Gap...

Spark Plug Gap is one of the most misunderstood things out there with the 'Internet' guys selling HEI clones...
Since they slap parts together, and don't really have a clue how they work electrically,
They recommend STUPID HUGE GAPS in the plugs and crappy wires...

The 'Average' ignition coil needs about 15,000 to 20,000 volts to successfully IONIZE a plug gap,
Then produce a spark.

The older breaker point ignitions were BARELY able to do that on a good day.
Breaker points are HORRIBLE for an ignition for a number of reasons,
Wear and ramp angle being the biggest two.

The HEI ignition has some limitations.
The coil in the cap has to be a SPECIFIC SIZE, so it will fit in the cap.
This limits the amount of insulation that can be use on the wire and between the windings.
It also limits the size and number of turns of wire in both windings,
And it limits the turn ratio inside between primary and secondary.

Now, how all that effects the spark plug gap...

When you jack the gap open,
The coil has to produce VOLTAGE to ionize that gap.
Without ionization, the spark can't form.

When you waste a bunch of the magnetic field collapse/induction created current formed in the secondary winding to building excessive voltage,
You LOOSE AMPERAGE AND DURATION of spark energy.

That magnetic field is only 'X' Strong, and it only moves for 'Y' time through the secondary windings, So you get 'Z' potential for secondary or spark energy current.

If you waste that 'Z' potential building VOLTAGE for an oversize gap,
Then you reduce the AMPERAGE, and the DURATION, or the time the spark lingers in the gap before the induction process ends.

With a spark gap around 0.030" to 0.032" like most stock Jeeps recommend,
You are only building about 30,000 volts, which is *Usually* enough to fire an overly rich fuel mix, low compression engine if the weather cooperates and things go 'Right'...

Throw in a properly adjusted lean fuel mix, some inclement weather, maybe some spark plugs with deposits on them, and you are NOT going to get that engine running correctly, if at all...
This QUICKLY explains all those EXTENDED 'Warm Up' times we need to get that engine running correctly.

Now, if you jack open the spark gap at the plugs, you do TWO THINGS real quick.
One is to need a LOT more voltage to ionize the gaps, that reduces the Amperage or 'Heat' in the spark, and you reduce spark Duration, the time that nice, hot spark lingers in the gap.

The second thing you you drove the voltage up, and with a small distributor cap and short factory rotor, you just created the PERFECT environment for the spark energy to jump to 'Ground' inside the cap or jump to the wrong plug terminal...

40,000 to 45,000 volts will fire the most stubborn, rich, fuel mix.
SO to keep the spark voltages of that magnitude under control,
HEI used a WIDE DISTRIBUTOR CAP that spaced the terminals farther apart.
They used a wider rotor to try and keep the spark energy from jumping to the distributor shaft/advance weights that are right under the rotor... (didn't work very well on the rotor part)

So with the wider cap to help control the spark energy, they started opening plug gaps up to drive up the voltage to the plugs required.

Now, if you are SMART,
You will stick with 0.040" to 0.045" plug gaps.
This will LIMIT the Voltage output required of the coil to about 40,000 to 45,000 volts.
Since that voltage range will fire ANY cylinder without ruining Amperage or Duration completely,
And that voltage range will fire any plug in any common vehicle burning gasoline,
There isn't any reason to waste any more of the coil induction cycle on voltage.

Produce a REASONABLE Amperage & Duration to get that fire lit!

When you open the spark plug gap up to 0.050 or 0.055" or larger,
You are KILLING the Amperage 'Heat' in the spark energy,
And you are killing the Duration of the spark in the plug gap.

You are also driving the VOLTAGE up so far the insulation on the rotor can't keep the spark energy from jumping to the shaft/weights inside the distributor,
And you are driving the voltage up so far the plug wire insulation is leaking through!

You have ALL heard of raising the hood in the dark and seeing 'Flashes' from the plug wires,
This is usually CHEAP WIRES, or way too much plug gap causing the problem.

You fight REALLY HARD, work really hard for the money for an ignition that will actually make spark energy to keep the engine running,
Why don't you shell out for a GOOD set of wires that will get that expensive and hard earned spark energy to the PLUGS!?

Putting some 'Color' wires on the engine to match your paint job is completely DEFEATING the money you spend on the stronger ignition!

With any SYSTEM, it's about the DETAILS, the support you give to the components in ALL AREAS of the ignition SYSTEM...

It's your vehicle, do what you want,
I'm just here to educate...
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Unread 01-20-2012, 09:09 PM   #5
I6CJ7
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Alright jeephammer, so can I use the starter relay as the switched power source for the HEI? Or your saying I can use that relay to turn on a dedicated power relay for just the HEI?

And its looks like it would be difficult to run a 10-gauge wire straight into the HEI as it is using a 14-gauge soldered to a small connector clipping into the unit. I suppose I could cut this off and solder the 10-gauge into instead.

If I understand correctly I can use the factory red 10-gauge power wire, which RIGHT NOW has a 14-gauge non-resistor wire connected to it, then to the HEI. Which I would then instead run that 14-gauge to turn on the power relay I would get. Then the power relay would draw it power directly from the battery, and have it directly grounded to the battery as well?

Just a side thought, I wonder if car audio "capacitors" that are used to store energy for when a subwoofer hits harder than the AMP can supply would be an effective way to store energy for the HEI as the coil discharges and recharges?

Also any diagrams you could post you might have on hand? Im an electrical noob!
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Unread 01-20-2012, 09:19 PM   #6
JeepHammer
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RELAYS...

A relay uses a SMALL voltage to pull in a larger set of contacts.
The smaller voltage creates a magnetic field, and that 'Electromagnet' pulls in the secondary higher voltage contacts for the larger current to operate without running large gauge wire everywhere,
And it also keeps the large load device closer to the power source.

Long wiring is an electrical restriction called 'Resistance'.
The longer the wire and the more load it carries, the more resistance you have.
Relays let you keep the heavy wires shorter, while controlling the circuit from a distance.



----------------------

TYPE OF COMMON AUTOMOTIVE RELAYS AND TERMINAL DESIGNATIONS.



NOTICE there are relays with fuses built into the housings for convince.
You can also use a small circuit breaker right next to the relay, and 'Zip' tie it to the relay for compact package and convince.


------------------------------------

EASY HEI INSTALL WITH A RELAY...



*TAKE NOTE*
The #85 & #86 terminals should be reversed from the diagram...
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Unread 01-20-2012, 09:48 PM   #7
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Quote:
Originally Posted by I6CJ7 View Post
Alright jeephammer, so can I use the starter relay as the switched power source for the HEI?
Or your saying I can use that relay to turn on a dedicated power relay for just the HEI?
I'm NOT telling you want to do,
But if it were me, when I do these HEI conversions or use an HEI distributor in a customers engine,

I DEDICATE a power wire to the HEI, and use a RELAY to switch that dedicated power supply to the HEI.

Quote:
And its looks like it would be difficult to run a 10-gauge wire straight into the HEI as it is using a 14-gauge soldered to a small connector clipping into the unit. I suppose I could cut this off and solder the 10-gauge into instead.
You can buy new terminals that go in that plastic connector off the rack at NAPA.
They cost about $2 a package.
There is a push tab on the metal part of the connector digging into the plastic housing,
Once that tab is pushed down, the wire and terminal will pull out of the plastic connector housing,

You crimp a new terminal on the wire you want to use, and push that new terminal right back into the plastic connector housing, and you are up and running with a larger gauge wire with a VERY clean looking connector.

------------------------------------

This is something that ALL NEW GUYS to electronics should learn...
The 'Loose Wire' connectors, like the ones for your dimmer switch, head light switch, brake light switch, head lights, fire wall bulk head connector, ect.

All have separate terminals inserted into a plastic housing.
These can be disassembled with a little inexpensive tool, and you can put in new wire or new terminal ends and freshen up your wiring without tearing the entire harness out...

Cracked insulation or frayed, melted wiring you want to replace without ripping out the entire harness?
We all have it,
The terminals are CHEAP, easy to install on NEW wire, and look 'Factory' when you are done.

--------

There are limits,
Since there are MOLDED TERMINALS on your vehicle also, like the ignition plugs for the stock distributor, module, ect.
These are molded right on the wire, and you can't replace the terminals in them.
But about everything else is 'Open' or 'Composite' terminals you can replace.

ANY TIME YOU HAVE A CONNECTOR APART, SHOOT SOME DIELECTRIC GREASE IN IT!
This keeps corrosion down and helps you keep your connections CONNECTED like they are supposed to be!

-----------------------------------------

Quote:
If I understand correctly I can use the factory red 10-gauge power wire, which RIGHT NOW has a 14-gauge non-resistor wire connected to it, then to the HEI.

Which I would then instead run that 14-gauge to turn on the power relay I would get. Then the power relay would draw it power directly from the battery, and have it directly grounded to the battery as well?
As near as I can tell from your description, YES. That's correct.
The OLD ignition wires switch the relay 'ON' and 'OFF'.
And the relay has a DEDICATED CLEAN SUPPLY, passing that on to the HEI.

Quote:
Just a side thought, I wonder if car audio "capacitors" that are used to store energy for when a subwoofer hits harder than the AMP can supply would be an effective way to store energy for the HEI as the coil discharges and recharges?
The ones sold in the audio stores are not the correct size/type.
That's EXACTLY what a CDI module does, Capacitive Discharges around 400 volts to the ignition coil...
Doesn't screw around with 12-14 volts and simply smoothing out the current to the coil/module like a audio capacitor would...

Quote:
Also any diagrams you could post you might have on hand? Im an electrical noob!
Yup, just hadn't got to them yet...
Wanted to explain the DON'T before I got to relays and wiring!
No one reads posts with pictures in them, so you have to get the WORDS in before pictures or you will get 10,000 questions that were already explained and never read...
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Unread 01-21-2012, 12:22 AM   #8
I6CJ7
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Awesome jeephammer, thanks for the great info and very clear diagram of how things should be set up!

Would a CDI module be something worthwhile using with my HEI? Or would it be overkill, since I'll be going the relay setup?
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Unread 01-21-2012, 04:28 AM   #9
John Strenk
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Quote:
Originally Posted by JeepHammer View Post
.....
No one reads posts with pictures in them, so you have to get the WORDS in before pictures or you will get 10,000 questions that were already explained and never read...
Boy am I guilty at this. I

Bought a BBD manual and rebuilt the carb looking at the pictures. The other night I was READING the manual and now I have to take the carb apart and fix it right.
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Unread 01-21-2012, 04:48 AM   #10
imafishingfred
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I had no intension of hi-jacking this thread, but, I found it very useful as I just installed a HEI dizzy in my sons 79 CJ7 w/304. I temporarily wired the power using the existing wire to the old coil. Notice I said temporarily. I plan to install a relay now that I have read and understand (sort of understand) the reasons for the relay.
In my thread I ask some questions about the wires going to the box on the fender. There are wires coming to it from the bulkhead connector. Can I now unplug all the wires to the box or is that a mistake? My thread is located here:
http://www.jeepforum.com/forum/f8/he...-gear-1311405/
Thanks for educating me on the proper way to wire the HEI.
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Unread 01-21-2012, 07:26 AM   #11
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Quote:
Originally Posted by I6CJ7 View Post
Awesome jeephammer, thanks for the great info and very clear diagram of how things should be set up!

Would a CDI module be something worthwhile using with my HEI? Or would it be overkill, since I'll be going the relay setup?
A CDI is worth while on most vehicles, particularly these old rich fuel, low compression dinosaurs.
Nothing like firing that plug 6 times per firing cycle where the factory style ignitions can only do it ONCE if we are lucky...

IF you wire directly to the HEI trigger and let the CDI unit do the switching to the coil,
You will find your coil puts out a LOT more spark energy per discharge,
Since the CDI modules use MUCH cleaner, faster switching than the HEI modules do.

Not only will you get 6 discharges per firing cycle, but you will get 6 MUCH MORE POWERFUL discharges than the HEI module can produce...

Spark energy is all about how FAST you can build that magnetic field to the saturation point,
And how FAST you can get the power circuit 'Open' so the magnetic field collapses at full strength through he secondary windings.

CDI modules achieve both of these objectives in spades!

----------------------------------------------

Quote:
Originally Posted by John Strenk View Post
Boy am I guilty at this. I

Bought a BBD manual and rebuilt the carb looking at the pictures. The other night I was READING the manual and now I have to take the carb apart and fix it right.
Me Too. I'm no exception.
We're men, throw something shinny in front of us and it completely distracts us from what we were doing...

I know this is the 'Geek' in me,
But I read new manuals in the bathroom.
After YEARS of screwing things up, I now take a pen, actually READ the text,
HIGHLIGHT important information,
And I write clearances, stuff I should be aware of, IN THE PICTURES on the page!

That way, when I SKIM the manual looking at the pictures in the garage, I have the clearances, ect. in the PICTURE, so maybe I'll actually take notice...

You NEVER want a 'Used' manual from me!
They all look like an epileptic chicken has been dancing in ink then on the manuals!

-------------------------------------


Quote:
Originally Posted by imafishingfred View Post
I had no intension of hi-jacking this thread, but,
I found it very useful as I just installed a HEI dizzy in my sons 79 CJ7 w/304.
I temporarily wired the power using the existing wire to the old coil.
Notice I said temporarily.
I plan to install a relay now that I have read and understand (sort of understand) the reasons for the relay.

In my thread I ask some questions about the wires going to the box on the fender.
There are wires coming to it from the bulkhead connector.
Can I now unplug all the wires to the box or is that a mistake?
My thread is located here:
http://www.jeepforum.com/forum/f8/he...-gear-1311405/
Thanks for educating me on the proper way to wire the HEI.
I've been working with HEI's for around 40 years now...
I had some of the best engineers point out the flaws with the HEI (and about all other ignitions/components) also.

You can't learn all this overnight, so I'm trying to condense,
And for guys that never studied electrical properties, it's like trying to lean astrophysics in a couple of days without math classes to lay the basis for the learning curve.

I visited your thread, left a kernel there for you.

The 'Best' place to hook up from a 'Factory' harness is the old module power connector.
It's a 10 Ga. wire, no resistor, and available since you aren't using the factory module anymore, it's otherwise an unused circuit...

I will do MUCH better than your old coil wire positive feed since that coil wire had a resistor in line, besides all the other problems...
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Unread 01-21-2012, 10:53 AM   #12
I6CJ7
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What brand and model of CDI would you recommend I use Hammer?
And how difficult is it setting one of those up? After I setup the relay, would I take the power wire coming from it, then to the CDI, and from there straight to the HEI's power clip?
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Unread 01-21-2012, 11:37 AM   #13
swatson454
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Will you be able to give us before and after results?


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Unread 01-21-2012, 11:44 AM   #14
JeepHammer
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Quote:
Originally Posted by I6CJ7 View Post
What brand and model of CDI would you recommend I use Hammer?
And how difficult is it setting one of those up? After I setup the relay, would I take the power wire coming from it, then to the CDI, and from there straight to the HEI's power clip?
you wouldn't use a relay for a CDI.

The CDI has the following,

TWO LARGE WIRES to the battery or battery cables to power it's self up.

Two wires to the ignition coil so the CDI can take control of that coil.

Two wires to the distributor trigger, so it knows when to fire,

One wire to the ignition switch, so it knows when to turn 'On' and 'Off'.

Since it takes it's power directly from main battery supply or large cables,
There isn't a relay needed.

Since it takes the trigger signal directly from the distributor trigger, you don't need the module in the distributor anymore.
I DO suggest you leave that module in place so you have a REDUNDANT ignition if the CDI ever fails.

Since the CDI drives the coil directly, you simply unplug the module to cap plug, tape it over,
And connect the CDI directly to the cap.

NO POWER WIRE TO THE CAP, NO RELAY TO POWER UP THAT WIRE, ECT.

If the CDI fails,
You flip the cap, unplug the CDI wires from the trigger, plug the module back in internally,
You plug the module back into the cap, and you hook up a power wire back to the cap terminal to get you home.

Nothing like having a REDUNDANT ignition waiting in the wings!

-----------------

As for brand,
I like MSD, but I'm bias...
MSD is the inventor and best manufacturer for several years,
But the company has sold out to a 'Conglomerate' and like all big buyouts, the parent company has been cutting corners, and the quality is suffering for it.

If you get an MSD, and anything EVER happens to it, they have traditionally fixed it for free no mater how old it was.
I don't know how much longer that is going to last, but since the 70's its been a GREAT THING!

Now the basic MSD CDI module is being made in 'China' and places like Summit have their own versions that are IDENTICAL internally to the older style MSD modules.
I can't swear to component quality, but the circuits are identical since the basic MSD module has been out from under patent for several years, this was BOUND to happen sooner or later.

And since it's still a good, solid design that works well, there isn't anything wrong with it *IF* the components are the same quality that MSD used to use.

DO NOT get the 'Marine' or 'Off Road' versions!
They are EPOXY POTTED, meaning the case is filled with epoxy to keep things from getting wet or rattling loose...
(Which I don't have problems with anyway, and I beat the hell out of mine!)

Once filled with epoxy, it's NON-SERVICEABLE, so unless you intent to run it under salt water or beat on it with a hammer all day, you don't really need the epoxy filled version.
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Unread 01-21-2012, 12:49 PM   #15
I6CJ7
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Good stuff hammer, I will start looking online at different CDI and see what I like. Although im on the fence as to whether to just go with the relay, and power the HEI this way. Or be different and go with CDI which sounds interesting... I definitely agree with a redundant system in place as I had a HEI module go bad on the road luckily! And I had no spark, I jist happend to remember from reading an article years ago that this can happen and what causes it... wej to advanced auto, got a new one, threw it in... fired right up!

I will definitely need a diagram how to wire in the CDI into the HEI. And I'll use put a female connector a Y split off the old HEI power wire should the CDI fail I can quickly hook it back up to the HEI's original coil, correct?

And Shawn I will definitely post some results of before and after. Right now I have a CRT brand HEI clone, its worked quite well, especially after taking out the resistor wire that was powering it!
The distributor is uncurved and not adjusted at all, but has worked very well for me, very quick acceleration and no pinging. Even when towing loads as heavy as the jeep itself!
Although I do need to adjust my timing a tad based on some vacuum readings I took.

Finally because I dont have a DUI dizzy, and instead am using a clone offbrand, I willing to tune and tinker with all this stuff, whereas I wouldn't touch that $300 DUI!

Is there a place that can curve dizzys like DUI? Some place I could send mine?
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